Your consent is now also required for updates to apps on your smartphone or tablet.
Companies must also:
Clearly disclose to users if its software could collect personal information, interfere with the normal operation of a computer, alter settings or preferences or data on a computer or allow a third party to access a computer. Those who fail to comply may be fined up to $10 million.
The law targets malware and spyware, but is controversial because it will also affect those who make or deal with legitimate software.
A previous part of the law targeting traditional email spam went into effect on July 1. It requires consent in order to send messages to customers via email, social media or instant messaging.
The messages must identify the sender, be truthful and allow the customer to unsubscribe.